1. Field of the Invention
The present invention relates to processing performed to remove an abnormality on a data communication line, and to a printing process for the transmission of data along, for example, an IEEE 1394 line.
2. Related Background Art
Since for the performance of a communication process across a so-called centronics line only an image data source and a printer are connected together, basically, even when a physical line is disconnected, the canceling of a session is not required unless a user physically breaks the connection. And when data are being transmitted to other apparatuses, if a lower layer is disconnected from a line, accordingly an upper layer is immediately disconnected from the line.
Assume that, as provided for by the IEEE 1394 specification, a plurality of image data sources and a plurality of printers are connected together along a single, closed communication line. If, for example, one of the image sources that is connected to the line and that is transmitting data is disconnected, and if a printer that during a session communicates with that image data source continues to be connected to the source, as with a centronics line, the printer will be unable to transmit data to other image data sources on the line.
If an upper layer is disconnected immediately after a lower layer is disconnected, or if the disconnection and the re-connection of a line is performed due to the careless performance of an operation by a user or due to a rearrangement of apparatuses, the printing process must be repeated from the beginning. As a result, an undesirable, excessive expenditure of time, paper and ink (toner, etc.) occurs.
It is, therefore, one objective of the present invention to provide a communication control apparatus and a communication control method for re-connecting a system that, during a data transmission session, has been disconnected from a line due to the careless performance of an operation by a user, and a storage medium therefor.
To achieve the above objective, according to the present invention, a communication control apparatus comprises:
control means for, if a lower layer is disconnected while data is being transmitted to an apparatus, permitting an upper layer to continue to maintain a session for a predetermined period of time, and for, if a line connection is re-established within the predetermined period of time, permitting the upper layer to establish a connection for the transmission of data.
Further, according to the present invention, a communication control method comprises:
a control step for, if a lower layer is disconnected while data is being transmitted to an apparatus, permitting an upper layer to continue to maintain a session for a predetermined period of time, and for, if a line connection is re-established within the predetermined period of time, permitting the upper layer to establish a connection for the transmission of data.
Furthermore, according to the present invention, provided is a storage medium, on which is stored a communication control program, the communication control program comprising:
a control step for, if a lower layer is disconnected while data is being transmitted to an apparatus, permitting an upper layer to continue to maintain a session for a predetermined period of time, and for, if a line connection is re-established within the predetermined period of time, permitting the upper layer to establish a connection for the transmission of data.